DAVE00

iTrader: (10)

Guys,

Ok, here goes. I have a 95 T/A with a new compressor and dryer (installed) a few months back. I can't seem to get the air cooler than 65-68 deg - measured from center vent on full blast and cold. Here's what I've done:

Fully Evac'd the system and charged with 2 lbs - r134a
Proper amount of pag oil
Compressor is cycling and staying on normally
Fully flushed system - zero restrictions
System is holding pressure (several months now) and no leaks detected with dye
Evap core is clean and blower is working great with zero debris
Condensor is clean and no restrictions or debris
Temperature door seems to be working fine as I can switch between heat and cold no problem.

Now my recent pressure checks came back normal again with 35 (low) and 250 (high) at around 95 deg with 40%+ humidity in my garage. According to the LT1 specs this is normal and since I have no leaks and the system should be free of air I should be getting 55-60 at the vents as a max?

Am I just loosing it or what is going on here?

The low pressure side hose coming from the TXV (Thermal Expansion Valve) is cold and condensing as it should and the High Pres side going in is hot. Could my TXV have a problem and if so what symptoms should I be looking for? I'd really appreciate any advise here?

guppymech

iTrader: (7)

It sounds to me like your AC sys is serviced okay. Looking at my '94 GM service manual page 1B1-3 there is a simplified drawing of the HVAC sys. If your tempurature valve (heater core door) controlled by the temp **** is not isolating the heater core hot air will dilute the cold air from the evaporator. You could try to measure the temp of the air coming out of your vents with the engine up to operating temp in the garage as to avoid solar heating of the interior. Compare the temp of the vent air with the HVAC sys just running full cold, fan on with the AC OFF to ambient temperature. The temp coming out of the vents should be close to ambient if the heater door is closing properly.

guppymech

iTrader: (7)

Do you have the factory service manuals? They are very helpful.

From the manual:
for 95 deg OAT with 40% humidity gage pressures are, Low side 25-42psi, High side 165-260 psi, center outlet temp 45-63 deg F, Evap temp 40-58 deg F (temp signal from evap temp sensor to PCM).

Your numbers are close to these. Is the PCM cycling the compressor to prevent the evaporator from freezing over?

DAVE00

iTrader: (10)

Thanks guys the measurements listed in my post are with the a/c full cold, car at op temp and in the garage with a fan blowing over the condenser. I'll try the suggestions about the temp door and ambient temp and let u know. Not sure about the PCM cycling the comp as I can't hear it disengage with this cam (lol) but is it supposed to cycle? I dont think the evap is freezing over as the velocity of air at the vents does not diminish. Any other suggestions?

defaultexistence

iTrader: (11)

Your hvac flap/door fro heat/cold selection may nit be fully closing.... Maybe because of low vacuum from the cam? You may need a vacuum can.. I experienced that issue slightly with my cammed 98 T/A and was told all this by an A/c shop..

shbox

The temperature door is controlled by a cable for our system. Not sure if 98 is the same.

http://shbox.com/1/hvac_vacuum.jpg

http://shbox.com/1/ac_performance_chart.jpg

96TransAmboosted

iTrader: (8)

Your system is very close to working properly. Did you use gauges when installing the freon? Maybe over charged the system by chance?

DAVE00

iTrader: (10)

This is a possibility, but pretty sure I measured it out right around 2lbs for the system. Just sux that I can't get it cooler as my wife's burb and my 04 BMW 330i blow ice cold and make this thing feel like a fan in a tent camping vs an A/C.

jaycenk

iTrader: (1)

If the condenser is stock and has never been out of the car I say it's clogged. I only say this because of when I removed mine and thought it looked clean as well but in reality the amount of crap stuck in the cooling veins was retarded. Even though I could see thought them, I ended up with a pile of dirt and organic crap from just wetting it and using compressed air to clean out the veins. Did this like 7 times and said F it, I'll buy another. It never let up on the amount of crap coming out off it. lol I thought someone was playing a joke on me it was so strange like it was never ending but the crap kept coming out.

DAVE00

iTrader: (10)

I don't think it's the condensor as the car only has 49K and it looks pretty clean. I have cleaned it with air and evap/coil cleaner and it does seem to be doing the job. The low side line (after it goes thru the TXV) does get good and cold and condenses water as you would expect. I really think it's either over or under charged and I'm going to go ahead and pull a vac on it again and let it sit over night to triple check I don't have any leaks and then recharge when I'm sure.

jharris

iTrader: (2)

Why 2lbs of 134? is that what the system calls for?

Also TXV will fail closed if the sensing bulb loses the its pressure it the head.( the most common cause if failure) Here is a link on TXVs and TEVs http://www.central-air-conditioner-a...ion_valve.html I know it shows residential systems but TXVs in all cases they work the same.

DAVE00

iTrader: (10)

Yes that is what our systems call for. As to the TXV, thanks for the link.

formula vincent

iTrader: (1)

did you replace the expansion valve? that "block" looking thing that has the two
lines going to it in front of the a c housing . its basically a "new style" orifice tube.it
probably has some junk in it from the old compresor thats affecting the pressure levels
in the ac system .

DAVE00

iTrader: (10)

Nope, and actually orifice tube's are a newer/cheaper style or alternative to the traditional TXV. I pulled it yesterday and it looked clean and when I replaced the compressor several months back the system was fully flushed, even tho the compressor just had the typical case leak and never took a dump in the system. Anybody else know any symptoms of the the TXV going bad? I purged the system last night and pull a vac on it and it's held -.5 vac all night so the system looks pretty good and leak free.

formula vincent

iTrader: (1)

well today on the drive home i had the ac running .then all of a sudden i
had hot air coming out the vents. looked underhood when stopped. saw
the compressor clutch "binding "im glad the belt didnt break as it was still
spinning free on the clutch pulley. when i put the new compessor on the
car 18 months ago i forgot to install a new TES valve i hope this solves
all the ac headaches i been having with this car... it sucks not having ac.
btw my 94 formula is red and a hard top too.

jaycenk

iTrader: (1)

It's been 90+ deg since may here in florida and I have not had A/C since the compressor died last year. Need less to say I have not been able physically stand driving it even at 9pm at night.

cookietime

smy ac puked this weekend, after lots of research, learned that refrigant was low.
My condenser wasnt kicking in, so hot wired the relay , B1 to B4 , and condenser started working..(just a test)
I didnt have a scan tool to check or clear codes, so unhooked the battery for 10 minutes,replaced relay , and recharged system, and works great for now. somewhere here theres a thread with more info,
way too hot . ggood luck
and anything lasting for more than 4 hours call your doctor

http://www.ls1lt1.com/forum/lt1-%7C-...ot-engage.html